For example, the first phone, called SoMo1, gives its user a mild electric shock, depending on how loudly the person at the other end is speaking. This encourages both parties to speak more quietly, otherwise the mild tingling becomes an unpleasant jolt. Such phones, the designers suggest archly, could be given to repeat offenders who persistently disturb people with intrusive phone conversations. (...)

SoMo4 replaces ringtones with a knocking sound: to make a call, select the number and knock on the back of the phone, as you would on somebody's door. The recipient of the call hears this knock (cleverly encoded and relayed via a short text-message) and decides how urgent the call is. How you knock on a door, says Mr Pullin, is freighted with meaning: there is a world of difference between tentative tapping and insistent hammering. SoMo5 has a catapult-like device that can be used to trigger intrusive sounds on a nearby user's phone, anonymously alerting them that they are speaking too loudly.